1. Field of the Invention
This invention relates to methods for depositing polycrystalline Si-containing films and, more particularly, to methods for controlling the grain structure of such films.
2. Description of the Related Art
Polycrystalline silicon (also known as “polysilicon” or simply “poly”) is widely used in the microelectronics fabrication industry and has been described as “the work horse material of advanced devices,” see P. Van Zant, “Microchip Fabrication,” 4th Ed., McGraw Hill, New York, pp. 386 (2000). For example, polysilicon is used in MOS gates, as load resistors in SRAM devices, trench fills, multilayer poly in EEPROMS, contact barrier layers, emitters in bipolar devices, memory cell capacitor electrodes, and as part of silicide metallization schemes. Typical polysilicon deposition processes take place by thermal chemical vapor deposition (“thermal CVD”) in the 600° C. to 650° C. range, from either 100% silane or from gas streams containing silane and N2 or H2.